At present, a new special frame structure has been adopted at the physical layer in a base station to bear a Multimedia Broadcast/Multicast Service (MBMS) in the prior art, to further improve a transmission rate of the MBMS service in the 3GPP release 7.10
A schematic diagram of the special frame structure is shown in FIG. 1, and the frame structure includes one short slot and seven traffic slots, all of which are used for downlink transmission and transmitted in all directions. The short slot in the frame structure combines three special slots in the traditional frame structure, i.e. DwPTS, UpPTS and GP, into one slot with a length of 0.275 ms, and is used for transmitting a new type of burst data, such as transmission control information and the like. FIG. 2 shows the structure of the short slot, which includes a channel estimation code (i.e. a preamble) of 96 chips and data symbols of 256 chips. The seven traffic slots in the frame structure are used for transmitting the MBMS service. The structure of the traffic slot is shown in FIG. 3, and the traffic slot includes a channel estimation code (i.e. a preamble) of 96 chips and data symbols of 768 chips.
To ensure the compatibility with the existing system, i.e. to maintain the structure of slots in the existing traditional frame structure unchanged, another new frame structure is also adopted at the physical layer in the base station in the prior art to bear the MBMS service, and has a structure as shown illustratively in FIG. 4, which includes 3 idle slots, 1 slot TS0 and 6 traffic slots TS1-TS6. All of the slot TS0 and the slots TS1-TS6 are used for downlink transmission, while the three idle slots between the slot TS0 and slot TS1 are used for neither downlink transmission nor uplink transmission.
Based on the above two frame structures at the physical layer described above, when a Node B is instructed by a Radio Network Controller (RNC) to establish an MBMS over Single Frequency Network (MBSFN) cluster, two types of MBSFN clusters may be established, one of which is an MBSFN cluster where the MBMS service is transmitted based on the first physical layer frame structure described above, and the other is an MBSFN cluster where the MBMS service is transmitted based on the second physical layer frame structure described above.
In the prior art, there is neither a method for searching for a desired MBSFN cluster from the MBSFN clusters where the MBMS service is transmitted based on the above-described two types of physical layer frame structures, nor a method for receiving the MBMS service from the searched out MBSFN cluster, as a result, a User Equipment (UE) can receive the MBMS service from neither of the above-described two types of MBSFN clusters.